*this article was written summer 2002, but the same applies for today, although of course the speeds are markedly higher - the key point is that the marginal costs is very high for the extra bit of top speed.

Quality thresholds.
   When buying computer parts or when purchasing a whole system, the most important thing is arguably to get the best 'bang for the buck'. This brief section details an important factor when deciding upon what to buy - what i shall call the price-quality ratio.
A great example to use is that of the CPU, the core processor of any computer system.

The fact is that there comes a point where purchasing a faster processor becomes totally insane - the marginal 100mhz increase in speed, is at a massive disproportionate cost.

There are some odd price/quality ratios. The price ratio is actually a touch more favourable at the 1.7Ghz speed, than at the lower speeds of 1.4 and 1.5Ghz. 

Most noticeable is how the price of the 2.4Ghz processor is twice as costly per 100mhz than the slower processors.

* all prices based on quotes 10/8/02 via online retailers.

The key point, is to pick a processor- or indeed any computer product that is a few levels below the 'cutting edge', yet is still relatively ahead of the main product quality.

In the case of the Pentium 4 processor, it makes sense to purchase something between 1.7 and 2.2Ghz.
It would take an extremely insane (or  rich) consumer, to decide to buy anything above the 2.2Ghz level. 
Besides, current applications, even the video intensive ones are not going to benefit much more - due to other bandwidth issues (remember, the computer only runs as fast as the slower part).